Results from POLI: Magnetic Monopoles in a Metallic Compound


An international team of researchers, including scientists from the Institute of Crystallography Dr. Hao Deng and Dr. Vladimir Hutanu at the branch of the institute in the MLZ Garching, has now discovered monopoles in a “Kagome spin ice” material, which is electrically conductive and could therefore offer great potential in scientific and practical applications. The results have been published in the journal Science.

The scientists carried out essential parts of the experimental investigations on the intermetallic compound HoAgGe with a research instrument jointly operated by Forschungszentrum Jülich and RWTH Aachen University at the Heinz Maier-Leibnitz Zentrum in Garching near Munich. Using the high-field superconducting magnet recently commissioned at the neutron diffractometer POLI, they could determine the orientation of the single interacting magnetic moments of the atoms in the crystal lattice, the so-called magnetic structure. "This can only be done by neutron diffraction," explains the instrument scientist, Dr. Vladimir Hutanu. “With POLI, we can perform these measurements precisely as a function of temperature and magnetic field. We use the instrument to study complex magnetic structures also in other materials with application potential, such as novel quantum materials, for example, representing a research focus at the Jülich Center for Neutron Science (JCNS). ” The scientists from Jülich and Aachen carried out both the neutron measurements and also participated in the analysis of the results, in cooperation with their international colleagues.

  Instrument POLI with 8-Tesla-Magnet and results Copyright: © MLZ

The new 8-Tesla magnet on the instrument POLI which the scientists used for their experiments (left). In HoAgGe, the Ho spins build a Kagome lattice structure. The arrows indicate the orientation of the spins (right-top). Magnetic moments in the plane follows the ice rule in triangles: “two-in-one-out”, namely one positive magnetic charge, or “one-in-two-out”, namely one negative magnetic charge, forming a honeycomb lattice of magnetic monopole quasi-particles (right-bottom).


Original publication:

Kan Zhao, Hao Deng, Hua Chen, Kate A. Ross, Vaclav Petříček, Gerrit Guenther, Margarita Russina, Vladimir Hutanu und Philipp Gegenwart: Realization of the kagome spin ice state in a frustrated intermetallic compound. Science, 13 Mar 2020: Vol. 367, Issue 6483, pp. 1218-1223, DOI: 10.1126/science.aaw1666


Detailed information of the University of Augsburg, “Metallic compound with magnetic monopoles“, 18.02.2020

Press release of the MLZ Garching, “North pole without south pole: Magnetic monopoles detected”, 20.03.2020

Press release of the FZ Jülich, “Magnetic Monopoles in a Metallic Compound”, 23.03.2020

Press release of the HZB, „Neutron research: Magnetic monopoles detected in Kagome spin ice systems“, 07.04.2020



  Dr. Vladimir Hutanu Copyright: © MLZ

Dr. Hao Deng

  Dr. Vladimir Hutanu Copyright: © MLZ

Dr. Vladimir Hutanu